The present invention relates to novel carriers or vehicles for spermicidal substances and in particular to the use of modified dextrans as novel vehicles of spermicidal substances in compositions used in local contraception.
It is known that local contraception with chemical agents is based on the use of spermicidal substances contained in tablets, suppositories, creams, solutions for spray applications, etc., which immobilize or kill the sperm cells, preventing them from running up through the female birth canal and avoiding thus a meeting with the ovule.
In reality the use of hitherto known preparations has certain limits mainly due to the difficulty of satisfactorily bringing into contact the spermicidal agents with the sperm cells. It can occur in fact that at the time of ejaculation, a portion of the sperm is directly sucked into the cervical canal and runs up through it without stopping in the vagina where the spermicidal substances are staying. This is one of the reasons for the failures which are met with by such an contraceptive method.
Also the use of sparkling, foaming and surfactant substances which promote an even dispersion of the spermicidal agents in the vagina has not allowed to notably improve the trust index of the local contraceptive agents, which are therefore the least reliable anit-fecundative methods among the ones not based on the menstrual cycle.